The invention relates to a process for extracting solid materials using an organic solvent and relates more particularly to units having to operate continuously under the following working conditions:
large variety of plant materials to be extracted,
numerous different solvents,
very numerous successive runs using different solvent/solute associations, each run being of short duration,
reduced qualification of the operating personnel.
The invention also relates to the apparatus for implementing the process.
The technique usually used for separating the solvent is that of fractionation which comprises a distillation column with trays or packing, a column head vapor condenser and possibly a column bottom reboiler. Depending on the characteristics of the solvent/solute pair and on each of the components of the pair, there is modification of the fundamental characteristics of the fractionation column such as:
feeding height of the fresh feed,
type of packing,
number of trays.
The treatment of very numerous solvent/solute pairs forces manufacturers to invest in very sophisticated (fractionation) equipment with multiple possibilities of adjustment, dismantling and modification so as to be able to cope with the extended range of its operating conditions.
The manufacturer must in addition have a highly qualified staff capable of carrying out the adjustments, dismantling operations and modifications which take place between runs.
Finally, so as to limit the impact of the cost and the length of these adjustment, dismantling and modification phases on the exploitation, the industrialist will attempt to extend the duration of the runs with the same solvent/solute pair while taking risks that the basic products or the intermediate products stored waiting for treatment are degraded.
The Applicant has sought to avoid these drawbacks by:
a process simple to put into practice making it possible to use readily constructed equipment,
flexibility of use based on the modification of the reference values of the control variables of the process rather than on the configuration of the installation for implementing the process,
easy automation of the operation because of the continuous operation and the reproducibility of the control variables.